1. Technical Field
The present disclosure relates to slave/external devices interfacing over serial buses and more specifically to establishing communication over such buses (e.g., USB) in the slave devices.
2. Related Art
Serial buses are often used to connect external devices to a host device. In general, a serial bus represents a bus in which data symbols/bits are transferred serially on a single signal path (implemented either using single ended signal or differential signal). Universal serial bus (USB) and I2C, well known in the relevant arts are examples of such serial buses.
The external devices are often referred to as slave devices since multiple slave devices are connected to the same host device and the host device controls the operation of the slave devices in several respects (e.g., such as allocating an address, determining speed of operation, etc.).
Communication needs to be established between a slave device and the host device before transfer of substantive data (i.e., the data used by various applications implemented in the devices). Establishing a communication implies making devices in the two sides ready for transfer of application specific data. Typical tasks in communication establishment include one or more related tasks such as synchronization, enumeration (identifies the various parameters, such as allocation of address, to communicate with the slave device), etc. In general, any necessary configurations are performed internal to both the devices, based on the exchanged/determined information to complete establishing Substantive data can be exchanged between the two devices once communication is thus established.
The communication is typically established soon after the slave device is plugged into a connector present in the host device. Establishing communication entails exchanging data packets consistent with the protocol specification to perform tasks such as enumeration, etc.
It is generally desirable that the logic underlying communication establishment meets the specific requirements of various environments in which the slave device is used.
In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The drawing in which an element first appears is indicated by the leftmost digit(s) in the corresponding reference number.